Now that is really weird as setting the permissions is not something that the client machine actually see's happening. The smb.conf man page does say (about force directory mode") that
This parameter specifies a set of UNIX mode bit permissions that will always be set on a directory
created by Samba. This is done by bitwise 'OR'ing these bits onto the mode bits of a directory that
is being created
which would suggest to me that these setting will always add to the permissions, so if the dir is being created as 0700 or 0711 it will always end up as 0755. Take a look at the descriptions of the following parameters in the smb.conf man page, I'm sure that one combination must do the job!
- force create mode
- force directory mode
- force directory
- force security mode
- security mask
Sorry that I can't provide any more useful suggestions this isn't a behaviour I've ever seen (or ever realised was there).